The present invention relates to a measuring instrument in which, an inner frame supporting a pointer of a dial type indicator and an outer frame rotatably fitted on the inner frame and having attached thereto the scale plate of the dial type indicator, can be fastened together by compressively deforming an elastic element adjustably held in the inner frame, to thereby press it against the outer frame.
There are measuring instruments such as slide calipers and height gauges equipped with a dial type indicator. Such a dial type indicator has such a structure that an outer frame with a scale plate for a pointer is rotatably fitted around a circular inner frame rotatably supporting the pointer; and a zero point on the scale plate is set to the pointer by turning the outer frame with respect to the inner frame so as to effect zero ajustment.
In a conventional measuring instrument equipped with such a dial type indicator, a fixing means or locking means is provided to fix the outer frame against the inner frame to prevent rotation of the outer frame after zero adjustment, so that the zero position is not disturbed.
An example of such fixing means is disclosed, for example, in DIAL/VERNIER CALIPER GUIDE BOOK OF MITUTOYO CO. LTD. (1975, printed in U.S.A.). The guide book at page 9 illustrates a bezel clamp and bezel washer as the fixing means.
The bezel clamp includes a screw threaded into a plate or a ring of the inner frame. By tightening this screw, the bezel of the outer frame can be fixed to the inner frame by the bezel washer; and when said screw is loosened, the bezel can be rotated in relation to the inner frame. In such a fixing arrangement, when the bezel is fixed to the inner frame, the bezel washer pressed against the bezel, and the surface of bezel or the bezel washer are liable to be damaged. Since the bezel clamp and the bezel washer extend beyond the bezel, the bezel is sometimes hard to rotate for zero adjustment.